The single cylinder reciprocating engine has become widely used in the compressor and engine industry by reason of its low cost, light weight, reliability and versatility. Unfortunately it has one major disadvantage, namely vibration. The vibration of a single cylinder engine originates from the reaction of all of the following vibration forces on the casing of the device:
1. The rotating inertia forces of the crank and of the parts that revolve with it;
2. The reciprocating inertia forces of the piston and of the parts that reciprocate with it;
3. The inertia torque of the reciprocating parts;
4. The inertia torque produced by the pendulum motion of the connecting rod;
5. The torque variations produced by the varying gas pressure acting on the piston. A low cost solution to the vibration problem would make the single cylinder engine an ideal commercial mechanism. Attempts to solve the problem have been the subject of much research and experimentation. To eliminate the vibration it is necessary to deal with all five vibration sources. Efforts to date have been concentrated on the first three:
1. The rotating inertia forces can be completely eliminated by the use of rotating counterweights;
2. Elimination of the reciprocating inertia forces is possible by the use of dummy mechanisms or equivalent gear systems at a considerable sacrifice in cost, weight, reliability and simplicity;
3. Elimination of the reciprocating inertia forces eliminates the inertia torque produced by the reciprocating parts. Except for the possible use of rotating gears, no solution is known to exist for eliminating the inertia torque produced by the pendulum motion of the connecting rod. However, the torque created by oscillation of the connecting rod is small and is commonly neglected. This still leaves the vibration torque of the gas pressure differentials to be resolved. The only known solution to this is the use of multiple cylinder arrangements which only reduce the gas torque fluctuations at a considerable sacrifice in cost and simplicity.
An alternative solution to the inherent vibration problem of a single cylinder fluid pressure engine is to permit the engine to vibrate in space and seek to minimize the transmission of the vibratory forces to the base mount. Unfortunately such systems permit the drive shaft of the engine to orbit usually in all three planes so that power transmission to or from the shaft is difficult. While many proposals have heretofore been made, none has been found to provide a low cost practical solution to the problem.